1. Field of the Invention
The present invention relates to the internal mechanism of a motor and more particularly, to a carbon brush holder for motor.
2. Description of the Related Art
Taiwan utility model no. 290200 discloses a carbon brush holder, which comprises a copper conducting receptacle and a holder base. The copper conducting receptacle is made from a copper sheet material by stamping, having an upwardly protruded lead wire connection strip. The holder base has a vertical receiving hole. The copper conducting receptacle is fastened to the receiving hole of the holder base, keeping the lead wire connection strip extended to the outside of the holder base. Because the copper conducting receptacle is made from a copper sheet material by stamping, the wall thickness of the copper conducting receptacle is limited. Therefore, this design of carbon brush holder is not suitable for large current application.
Taiwan utility model no. 292024 discloses another structure of carbon brush holder. According to this design, the carbon brush holder comprises a copper conducting receptacle and a holder base holding the copper conducting receptacle. The copper conducting receptacle is made from a copper sheet material by stamping, having a lead wire connection upwardly protruded from the top side and a locating portion protruded from the outside4 wall. The holder base has a stop portion for stopping against the locating portion of the copper conducting receptacle after insertion of the copper conducting receptacle into the holder base. Similar to the aforesaid prior art design, this structure of carbon brush holder is not suitable for large current application.
FIGS. 11 and 12 show a conventional carbon brush holder 1 that fits for large current application. The carbon brush holder 1 comprises a copper conducting receptacle 2, which is extruded from copper and has a tubular configuration, a lead wire terminal 3 which is fastened to the top side of the outside wall of the copper conducting receptacle 2 with a rivet 4 and has a rectangular configuration, and an electrically insulative holder base 5, which comprises a upwardly extended vertical receiving hole 6 fitting the copper conducting receptacle 2. The wall thickness of the copper conducting receptacle 2 is determined subject to the required large current load. During actual practice, the upper part of the lead wire terminal 3 protruding over the top side of the copper conducting receptacle 2 is bent outwards for the connection of a lead wire. However, because the lead wire terminal 3 is fastened to the copper conducting receptacle 2 with a rivet 4, bending the upper part of the lead wire terminal 3 outwards causes loosening of the lead wire terminal 3 (see FIG. 12). Loosening of the lead wire terminal 3 may result in a short circuit.